Method of testing for tire leaks



March 30, 1965 H. s. MCCONKIE 3,

METHOD OF TESTING FOR TIRE LEAKS Original Filed Feb. 26, 1958 FIG. IFIG. 2 /2 HOWARD 5. McCONK/E BY 2w w @4 7 ATTORNEYS United States Patent3,175,390 METHOD (PF TESTING FOR TllRE LEA1 Howard S. McConlrie, 101Etter St, Hot Springs, Ark. Original application Feb. 26, 1958, Ser. No.717,624, new Patent No. 3,038,516, dated June 12, 1962. Divided and thisapplication Mar. 26, 1962, Ser. No. 182,397 2 Claims. (Cl. 73-49) Thisinvention relates to tires and more particularly to a tubeless tireprovided with one or more inner tubes for blowout protection and is adivision of copending application Serial No. 717,624, filed February 26,1958, now Patent No. 3,038,516, granted lune 12, 1962.

While tubeless tires have gained general commercial acceptance, they aresubject to a number of disadvantages. These include: vulnerability toblowout or sudden collapse with consequent danger to the occupants ofthe vehicle; difficulty in installing and need for special tools tomount the tires on wheel rims; the danger of rolling the tires oh thewheels on sharp turns when mounted on heavy or fast vehicles; theinability of readily ventilating the interior of the tire to preventrotting by water condensed therein; and the ditficulty of locating smallleaks or blemishes in the tire without dismounting the tire or thewheel.

It is a primary object of this invention to obviate these disadvantagesby provision within a tubeless type tire of an inner tube whose valvestem is air sealed to the rim upon which the tire is mounted to preservethe air sealing chamber within the tubeless type tire.

It is a further object of the invention to provide a plurality of aircompartments within a tubeless type tire so that the wheel may becontinued to be used safely even after sudden puncture of the tire.

Another object of the invention is to provide an inner tube within atubeless type tire, the tube being inflated to a much greater pressurethan the tire so as to carry most of the load while the lower pressurein the tire pre vents pinching of the tube, provides ventilation of thetube and tire, and provides atest pressure of the tire to determinesmall leaks, cracks and other flaws before they become serious.

Yet another object of the invention is to provide an inner tube for atubeless type tire which is easy to mount and inflate and which enablesthe tubeless type tire itself to be more easily mounted and inflated.

A further object is to provide in a safety tube, for use within aconventional tubeless type tire, a valve stem which protrudes through adifferent opening in the rim than that used for passage of the tireinflation valve stem, and which may be air sealed at said opening in anumber of ways including the use of a portion of the tube or tube stemto provide such air seal.

Another object is to provide multiple airways in one self-sealing valvestem. 7

The novel features that are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of specificembodiments when read in connection with the accompanying drawings,wherein like reference characters indicate like parts throughout theseveral figures and in which:

FIG. 1 is a side elevation of a Wheel assembly embodying the inventionwhich includes a tubeless type tire mounted on a drop center rim andassembled with an inner tube within the tire;

FIG. 2 is an enlarged section of the tire assembly taken on line 2--2 ofFIG. 1; and

FIG. 3 is an enlarged axial section of a combined tire 3,175,390Patented Mar. 30, 1965 and tube valve stem which may be used in place ofthe separate stems shown in FIG. 2.

Referring now to the drawings, the invention is shown in FIGS. 1 and 2embodied in an inner tube, indicated generally at 10, which issemifloated Within a conventional tubeless type tire 12 mounted on adrop center rim 14. The details of construction of the tire arewellknown to those skilled in the art and need not be described here. Itis sufficient to say that the tire has the usual tread 16, sidewalls 18and beads 20.

Tire 12 is inflated by means of one or more valve stems 22, FIG. 2, andassembled valves, not shown. The valve stem 22 is formed of resilientmaterial and pulled through an opening 24 in the rim 14. During thisoperation, the conical portion of the stem is compressed until the wallsof the rim opening 24 fall within an annular groove 26 in the valve stemat which time the walls of the stem groove expand to grasp the rimopening in air sealing engagement. The annular groove 26 is positionedbe tween the conical portion of the stem and a disclike flange 28. Thevalve stem is provided with a bore 30 for reception of a valve assembly.

The inner tube 10, which may also be of conventional construction asused with tubed tires, is slightly modified in the drawing, andcomprises a thin walled, endless rubber tube, doughnut shaped wheninflated, to which may be cemented, vulcanized, or otherwise secured, avalve stem 23 for protrusion through a second opening 36 in the rim 14.

The tire 12 may be inflated with air under pressure exceedingatmospheric pressure, and it is, therefore, of the utmost importancethat the opening 36 in the rim 14, for passage of the inner tube valvestem be air sealed to prevent loss of pressure in the tire. A number ofdifferent types of conventional inner tube valve stems may be usedprovided that they are modified to accomplish such air sealing of therim opening.

The tapered compressible valve stem 23 is similar to stem 22, but itsbase 28 is vulcanized to the tube 10 with the tube opening 34 inalignment with the stem lair channel 39. Between the disclike flange 28and the tapered portion 29, is formed the channel or groove 26 whosewalls engage the wall of the rim opening 36 with airtight pressure.

To mount the tire 12 and tube 10 on rim 14, one head of the tire isforced over the rim flange. The inner tube is then placed in the tireand the valve stem 23 is inserted in the rim opening 36 from the insideand pulled through the opening compressing the conical body of the valveuntil the valve stem groove 26 closes about the rim Wall surrounding theopening. If desired, the walls of the groove 26 may be coated withcement which upon hardening will further ensure permanent air sealing ofopening 36. The tubeless tire valve stem is similarly installed and thenthe second bead of the tire is mounted. The operator next inflates theinner tube with the desired mounting pressure. For example, thispressure may be in the order of 40 lbs./ square inch. The tube 10 willexpand to fill the entire space within the tire 12 forcing the beadededges 20 into air sealing engagement with the adjacent flanges of rim14.

Normally, tubeless type tires require a special tool to be appliedcircumferentially .to the tread to compress the tire radially and spreadthe side wall edges into sealing engagement with the rim, and such toolsrequire two men to position and operate them. The use of the inner tubewhose inflation accomplishes this task quickly and easily eliminates theneed for such special tools. There fore, an important advantage isderived apart from the safety gained by the double air chamber formed bythe addition of an inner tube.

The mounting tube is retained in the tire to function as a safety tube.Since the tube, during the mounting process, occupies all the tirespace, it can again fill the tire in an emergency. Tube pressure is nowreduced to the figure desired in an emergency, for example, 20 pounds.Then, air is applied to the tubeless tire valve stem and pressure raisedto the desired operating level, for example, 30 pounds. Since thepressure in the tire is higher than that in the tube, the latter will becompressed against its self-contained air and, at such time, thepressure in the tube will equal that in the tubeless tire air space.This pressure will compress the tube and move it away from the innersurface of the tire 12 leaving a space 48 completely surrounding thetube 10 except in the area where the tube is secured to valve stem 23.

The assembly of a tubeless type tire with an inner tube in the describedmanner presents a number of additional important advantages. First, ifthe tire 12 is punctured or blows out, no danger will result to theoccupants of the vehicle since the inner tube 10 will then expand tooccupy the entire space within the tire and the wheel may be driven inthis condition for an indefinite period of time.

Second, the space 48 between the inner tube and the tire preventspinching of the tube in contrast to normal tubed tires in which the tubecompletely fills the space inside the tire and is constantly subjectedto rubbing, chafing, and pinching by the inner wall of the tire.

Third, a tire pressure less than the pressure in the tube, andpreferably approximately lbs./ square inch, may be used as a testpressure to determine whether the tire has developed a slow leak, smallcut, crack or other slight imperfection. During this testing, the tubecarries the entire wheel load since it occupies the usual tire space asin a tubed tire. It may, if desired, be inflated to usual operatingpressure for the vehicle wheel. In many cases, it is likely that thetube will continue to be used with the operational pressure, and thetubeless tire test pressure be continued simply as a means of readilydetermining when any defect is developing in the tire. Such a defectwould cause the testing pressure to be lost and the tire could berepaired before any tube damage would result. Normally, tubes are notpinched and do not below out Without the tire having had a defect forsome time. The smallest defect will result in the loss of the testpressure.

During the usage of a test pressure, since it is less in pressure thanthe pressure in the tube, the tube will seemingly completely occupy thetire space, but this is never true in a tubed tire and it cannot be truein a tubeless tire. The volume of air involved in this testing pressureis very small. Such space and atmospheric air pressure in a tube tire iscommonly spoken of as a ventilating space and air. Since a tubeless tiremounts with air sealing engagement to the rim, this space can be servedwith any pressure up to but not equal to the pressure in the tube, andthe tube walls will not be effectively compressed. If on testing thepressure in the tire at valve stem 22, the pressure has dropped belowthe origin-a1 valve, it is an indication that a tire leak exists, and itcan be repaired before damage results.

FIG. 3 illustrates a multiple passage valve stem 63 which may be used toinflate both the tire and the inner tube, avoiding the need for twoseparate valve stems, such as 22, 23 shown in FlGS. 1 and 2. Stem 63comprises a tapered compressible outer body 65 connected to a truncatedbase 67 which may be of metal but may also be formed partially or whollyof resilient material. The outer body and base are separated by theannular channel 26 which seats the wall of rim opening 36 in air sealingengagement when. the stem body 65 has been pulled through the opening,as previously explained in connection with valves 22 and 23. The innersurfaces of the stem base 67 is vulcanized to the tube with the stembore 69 in alignment with opening 34 in the tube. A second bore 71 inthe stern terminates short of the inner surface of the stem has? andcommunicates with an angularly disposed air passage 73, partially orcompletely within the base 67, which opens into the tire space betweenrim t4 and the tube. The air bores 69 and 71 are lined by metalreinforcing tubes 75 and 79. A similar liner can be inserted or moldedin air passage 73.

Tube liners 75 and 79 are interrupted in their central portions exceptfor narrow strips 81 which connect the ends of the tubes. Thisconstruction permits the body 65 of the stem to be constricted whilebeing inserted and pulled into seating position in the rim opening 36,and gives an overall strength to the valve stem that would not exist ifsome of the metal of the liners did not extend through the rim aperturesection of said valve stem. This is particularly true when the base ofsuch valve stem is partially or wholly metal and such liners are therebyen abled become integral with such valve stem base metal. This featureis equally valuable for single airway valve stems since weights may beattached to such valve stems. The metal linears 75 and 79 are alsoadapted to support valve assemblies, not shown. When they are inserted,it will be apparent that the tube 10 may be inflated through passages 69and 34, while the tire may be infiated through passages 71 and 73. Thevalves seated in liners 75 and 79 independently permit the use ofdifferent pressures in the tire and tube.

It is to be understood that FIG. 3 is an illustrative embodiment whichcovers any compressible valve stem or valve stemlike device whichcreates an air seal with the rim when its annular groove is positionedunder compression within the walls of a rim aperture and providing thestem possesses no airway, or more than one airway. Plural airways wouldall lead from outside the tire rim assembly to air spaces within thetire including any tube or tubes contained therein. These airways mayhave in cross section any size or shape and be in any combination ofsuch. They may or may not have valve means in any combination since, inassuring ventilation for tires, it is desirable at times to be assuredof an open airway leading to the tire space outside the tube. Theairways may have metal or plastic linings, or any aprt of the same maybe partly or wholly lined with a substantially non-compressible liner.As an example, in FIG. 3, linings 75 and 79 may terminate near where thecutout 81 is shown. This would give the usual metallic lined stem forthe usual removable valve cores. Where no such linings are used andvalves are desired, valve cores will be screwed or otherwise insertedtherein and secured with air sealing engagement. The valve cores may beremovable or may be bonded in position.

The following explanation is directed to the importance of maintainingdifferent pressures in diifering air spaces of a tubed tire and of atubeless type tire with tube. A tubed tire contains atmospheric pressurebetween the bead and the rim, since it does not engage the rim in airsealing contact. There are also many irregularities of the tire innersurface and of the tube outer surface, which, though not visible to theunaided eye, do exist and are filled with air at atmospheric pressure.Some inner tubes have ridges formed in them to increase these air spacesso ventilating air can circulate more freely. Such ridges are also to befound occasionally around the inner periphery of a tube, and at timesencircling the outer periphery. While called by different names, theseridges all promote ventilation of the tubed tire with air at atmosphericpressure. The valve stem of a tubed tire is customarily left looselyfitting in the rim aperture in order to promote the ventilation of theinner surface of the tires.

Tubeless type tires, by definition, create an air seal with their rimsand to use the same for their intended purpose, all valve stems in therim must create an air seal therewith so that the tire rim assembly isin effect an air container. Multiple individual valve stems or a pluralairway valve stem which preserves this seal have been described. Theease of servicing such a plural valve stem tire when it is mounted on avehicle having fender skirts is readily evident.

Since it has been explained that tubed tires are ventilated by air thatexists and moves about between the tire and the tube, it can beunderstood that the same air space exists within a tubeless type tirewithin which is placed a fully inflated tube. In this case, that sameair space is an air container due to the nature of the air sealingtubeless type tire. Being an air contrainer, if a valve stem serves thisspace, air under pressure can be injected. As long as the pressure ofthe air in this space is less than that in the fully inflated tube, suchair does not use any more space than that originally occupied by the airpocketed under atmospheric pressure. This capability may be called theTire Perfection Test Pressure for even low pressure will be lost if thetire develops a defect or leak. Therefore, a tubeless tire containing afully infiated tube may operate for any length of time upon the fullyexpanded tube while permitting check of the low tire test pressure fromtime to time to most efficiently determine the slightest tire walldefect. A multiple airway valve stem, such as has been shown in oneembodiment in FIG. 3, will facilitate this new method of testing fortire defects.

Although certain specific embodiments of the invention have been shownand described, it is obvious that many modifications thereof arepossible. The invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

What is claimed is:

1. The process of testing a tubeless-type tire having an inner tubeexpandable to fully occupy the space within the tire, comprising thesteps of inflating the tube with an operating pressure sufiicient toengage the outer surface of the tube with the inner surface of the tire,inflating the tire with a test pressure less than that of the tube andinsutficient to compress the tube and disengage the outer surface of thetube from the inner surface of the tire, and subsequently measuring saidtire pressure to detect a tire leak as indicated by a measured tirepressure less than said test pressure.

2. The process of testing a tubeless type tire according to claim 1wherein said tire is inflated to a test pressure of approximately 5pounds per square inch while said inner tube is inflated to an operatingpressure of approximately 20 pounds per square inch.

References Cited by the Examiner UNITED STATES PATENTS 2,574,266 11/51Khalil 152340 2,915,035 12/59 Russell 1l6-34 3,065,763 1l/62 Howard152-340 X OTHER REFERENCES Article in June 1956 Tires-TBA Merchandising(publication), page 47 entitled From Goodyear: Two Chamber Safety Tires.

ISAAC LISANN, Primary Examiner.

ROBERT L. EVANS, Examiner.

1. THE PROCESS OF TESTING TUBELESS-TYPE TIRE HAVING AN INNER TUBEEXPANDABLE TO FULLY OCCUPY THE SPACE WITHIN THE TIRE, COMPRISING THESTEPS OF INFLATING THE TUBE WITH AN OPERATING PRESSURE SUFFICIENT TOENGAGE THE OUTHER SURFACE OF THE TUBE WITH THE INNER SURFACE OF THETIRE, INFLATING THE TIRE WITH A TEST PRESSURE LESS THAN THAT OF THE TUBEAND INSUFFICIENT TO COMPRESS THE TUBE AND DISENGAGE THE OUTER SURFACE OFTHE TUBE FROM THE INNER SURFACE OF THE